1. Field of the Invention
The present invention relates to a waterproof connector which is capable of ensuring waterproof characteristic in spite of the application for covered wires of different diameters.
2. Description of the Related Art
Japanese Unexamined Patent Publication (kokai) No. 9-320651 discloses a conventional waterproof structure for the connector. In the publication, there are shown covered wires each having a conductor covered with a synthetic covering part. In this structure, a pair of upper and lower resinous tips are used for a part of the structure where two covered wires intersect with each other.
The lower resinous tip is provided, at a center portion thereof, with a projecting welding boss and also provided, at the four corners, with guide grooves into which the covered wires are accommodated. Each guide groove has a cover removing part and a waterproof groove part, which are formed along a direction extending from the welding boss toward the outside, in order. There is remained a gap defined between each guide groove and the welding boss.
Similarly to the lower resinous tip, the upper resinous tip has a welding boss formed to project at the center portion and four guide grooves formed on four corners to define gaps between each guide groove and the welding boss. Also in each guide groove, a cover removing part and a waterproof groove part are formed in order.
According to the above-mentioned structure, on condition of setting the lower resinous tip in an amble, the covered wires are inserted into the guide grooves of the lower resinous tip so as to intersect with each other and sequentially, the upper resinous tip is turned over and abutted on the lower resinous tip. This abutment allows both welding bosses of the upper and lower tips to mutually contact with each other and also causes the covered wires to be interposed between the guide grooves. In this state, the resultant assembly is subjected to the ultrasonic oscillation by an ultrasonic horn exerting pressure on the upper tip.
Consequently, the cover parts of the covered wires are molten to enter into the waterproof grooves, so that both conductors are exposed and connected with each other. The further continuation of ultrasonic oscillating under pressure allows both of the welding bosses to be molten and welded to each other. In this state, the waterproof grooves are filled up with the molten resinous material forming the insulating cover parts. Thereafter, as time goes by, the molten material of the cover parts is hardened while fulfilling the waterproof grooves in the form of a ring, whereby the connection having the waterproof characteristic can be provided between the intersecting covered wires.
In this way, the above-mentioned waterproof structure allows the connector to have the waterproof characteristic. That is, according to the conventional structure, the waterproof characteristic is applied on the connector by forming the wire insertion holes of the connector body with the waterproof guide grooves and sequential fulfilling the grooves with the insulating cover parts molten by the ultrasonic oscillation.
However, if the thin covered wire having a small diameter is used for the structure, it is expected that the waterproof capability is not ensured sufficiently since an amount of the molten resin resulting from the ultrasonic oscillation is too little to fulfill the waterproof grooves. Accordingly, the application of the above-mentioned structure is limited to the covered wires having diameters more than a designated thickness disadvantageously.